Keratin fibers modified with combination of hard polymer forming and soft polymer forming monomers to improve quality of knitted goods made therewith



Patented Apr. 8, 1969 3,437,420 KERATIN FIBERS MODIFIED WITH COMBINA- TION OF HARD POLYMER FORMING AND SOFT POLYMER FORMING MONOMERS TO IM- PROVE QUALITY OF KNITTED GOODS MADE THEREWITH Edgar Dare Bolinger and Greville Machell, Spartanburg,

S.C., assignor to Deering Milliken Research Corporation, Spartanburg, S.C., a corporation of Delaware No Drawing. Filed Dec. 6, 1962, Ser. No. 242,639 Int. Cl. D06m 3/02 U.S. Cl. 8-1275 5 Claims This invention relates to a process for improving the flat stability of fabrics containing keratin fibers and to the fabrics so produced. 1

In the manufacture of garments from fabrics, the fabric is conventionally out while in a flat state into the desired pattern. Fabrics, however, and particularly knitted fabrics, tend to roll up from the cut edges after cutting, thereby greatly complicating the garment manufacturing procedure. To overcome this difficulty, garment manufacturers either glue or tape the cut edges to preclude them from curling.

This difliculty can be overcome in accordance with this invention by preparing the desired fabric from keratin fibers which have been reacted with a particular class of ethylenically unsaturated compounds.

Wool fabrics have been reacted with a wide variety of ethylenically unsaturated compounds, generally to impart to such fabrics a resistance to felting shrinkage effects or for experimental purposes merely to ascertain the effects on the fibers of reaction with various ethylenically unsaturated compounds. There has been no realization heretofore, however, that the particular class of ethylenically unsaturated compounds utilized herein could be reacted with keratin fibers to provide a high degree of flat stability in fabrics produced therefrom.

By flat stability as utilized herein is meant the property whereby a fabric tends to lie flat rather than curl up at the edges, even when cut, while lying in a flat state.

The class of ethylenically unsaturated compounds suitable for use in accordance with this invention includes those compounds which in polymer form, have a glass transition temperature less than about 40 C., preferably below about 0 C.

The glass transition temperature is a well-known property and is the temperature at which a sheet of a polymer is transformed from a glass-like solid state to a softened state. Above the glass transition temperature, the volume of the sheet increases more rapidly with an increase in temperature. The point at which this volume increase begins may be readily determined in a plot of volume versus temperature. These glass transition temperatures may be readily determined by standard A.S.T.M. heat deflection temperature measurements, e.g., A.S.T.M. Designation D648-45T, issued 1941, revised 1944, 1945.

Among the suitable compounds, there are included the acrylic acid esters of unsaturated aliphatic monohydric alcohols, for example, methyl, ethyl, a-chloroethyl, propyl, isopropyl, butyl, isobutyl, amyl, isoamyl, hexyl, heptyl, octyl, 2-ethyl hexyl, nonyl, decyl, and the like and methacrylates containing more than two carbon atoms in the ester grouping. An optimum balance of reactivity and improved properties is found in those esters containing from 4 to 8 carbon atoms in the ester grouping,

acids, e.g., vinyl propionates, valerates, laurates, etc; vinyl pyridine, vinyl pyriole and the like, as well as hydroxyalkyl esters of acrylic and methacrylic acid, such as hydroxyethyl acrylate, hydroxymethyl acrylate, t-butylaminoethyl methacrylate and the like.

While some improvement in fiat stability is obtained at any significant pickup of the above compounds, e.g., above about 10% by weight, the desired improvement is obtained to a significant level only at pickup levels exceeding about 50% by weight of the above compounds.

Although ethylenically unsaturated compounds having glass transition temperatures in excess of about 40 C., particularly in excess of about C., generally do not provide the desired improvement in flat stability, such compounds may be blended with ethylenically unsaturated compounds having glass transition temperatures below about 40 C. to provide such improvement, provided the latter class of compound is present in at least a major proportion.

In addition to flat stability, it has been found that fibers treated in accordance with this invention retain crease angles after immersion in water to a degree comparable to untreated wool, so that fabrics having essentially the same creasability as untreated fabrics, with greatly improved flat stability, may be produced in accordance with this invention. Furthermore, by treating loose fibers in accordance with a preferred embodiment of this invention, feltable fabrics of superior hand and physical properties are obtained.

This improved flat stability enhances the manufacture of garments from both woven and knitted fabrics, particularly the latter. Furthermore, the heavy rib conventionally knitted along the edge of knitted fabrics to prevent curling may be greatly reduced in size or eliminated where unravelling can be otherwise avoided.

Ethylenically unsaturated compounds may be reacted wit-h keratin fibers through a number of well-known processes. For example, keratin fibers may be reacted with the desired compounds in the presence of a catalyst or initiator system for inducing polymerization of the compounds. Among such systems, there are included azo catalysts, such as azobisisobutyronitrile, as well as irradiation under the influence of high energy fields, including the diverse actinic radiations, such as ultra violet X-ray and gamma radiation as well as radiations from radioactive materials such as cobalt-60.

In general however, it is preferred that the reaction of keratin fibers with ethylenically unsaturated compounds be conducted in the presence of a redox catalyst system, Le. a catalyst system composed of a reducing agent and an oxidizing agent initiator. Although the catalytic mechanism is not completely understood, it is believed that the interaction of these agents provides free radicals which cause polymerization of the compounds, which preferably are in monomeric or low polymeric form, onto the keratin fibers.

The reducing agent may be an iron compounds, such as the ferrous salts including ferrous sulfate, acetate, phosphate, ct-hylenediamine tetra-acetate; metallic formaldehyde sulfoxylates, such as zinc formaldehyde sulfoxylate; alkali-metal sulfoxylates, such as sodium formaldehyde sulfoxylate; alkali-metal sulfites, such as sodium and-potassium bisulfite, sulfite, metabisulfite or hydrosulfite; mercaptan acids, such as thioglycollic acid and its water-soluble salts, such as sodium, potassium or ammonium thioglycollate; mercaptans, such as hydrogen sulfide and sodium or potassium hydrosulfide; alkyl mercaptans, such as butyl or ethyl mercaptans and mercaptan glycols, such as beta-mercaptoethanol; alkanolamine sulfites, such as monoethanolamine sulfite and mono-isopropanolamine sulfite, manganous and chromous salts; ammonium bisulfite, sodium hydrosulfide, cysteine hydrochloride, sodium thiosulfate, sulfur dioxide, sulfurous acid and the like, as well as mixtures of these reducing agents. In addition, a salt of hydrazine may be used as the reducing agent, the acid moiety of the salt being derived from any acid, such as hydrochloric, hydrobromic, sulfuric, sulfurous, phosphoric, benzoic, acetic and the like.

Suitable oxidizing agent initiators for use in the redox catalyst system include inorganic peroxides, e.g., hydrogen peroxide, barium peroxide, magnesium peroxide, etc., and the various organic peroxy catalysts, illustrative examples of which are the dialkyl peroxides, e.g., diethyl peroxide, dipropyl peroxide, dilauryl peroxide, dioleyl peroxide, distearyl peroxide, di-(tert.-butyl)peroxi-de and di-(tert.-amyl)peroxide, such peroxides often being designated as ethyl, propyl, lauryl, oleyl, stearyl, tert.-butyl and tert.-amyl peroxides; the alkyl hydrogen peroxides, e.g., tert.-butyl hydrogen peroxide (tert.-butyl hydroperoxide), tert.-amyl hydrogen peroxide (tert.-amyl hydroperoxide), etc.; symmetrical diacyl peroxides, for instance peroxides which commonly are known under such names are acetyl peroxide, propionyl peroxide, lauroyl peroxide, stearoyl peroxide, malonyl peroxide, succinyl peroxide, phthaloyl peroxide, benzoyl peroxide, etc.; fatty oil acid peroxides, e.g., coconut oil acid peroxides, etc.; unsymmetrical or mixed diacyl peroxides, e.g., acetyl benzoyl peroxide, propionyl benzoyl peroxide, etc.; terpene oxides, e.g., ascaridole, etc.; and salts of inorganic peracids, e.g., ammonium persulfate, potassium persulfate, sodium percarbonate, potassium percarbonate, sodium perborate, potassium perborate, sodium perphosphate, potassium perphosphate, etc.

Other examples of organic peroxide initiators that can be employed are the following: tetralin hydroperoxide, tert.-butyl diperphthalate, cumene hydroperoxi-de, tert.- butyl perbenzoate, 2,4-dichlorobenzoyl peroxide, urea peroxide, caprylyl peroxide, p-chlorobenzoyl peroxide, 2,2-bis(tert.-butyl peroxy) butane, hydroxyheptyl peroxide, and the diperoxide of benzaldehyde.

The above oxidizing agent initiators, particularly the salts of inorganic peracids, may be utilized alone to initiate the reaction, although faster reactions at lower tempera tures may be conducted when the oxidizing agent is combined with a reducing agent to form a redox catalyst system. Ferric salts can be used as oxidizing agents and form a redox catalyst system with hydrogen peroxide, in which case the peroxide functions as a reducing agent.

The reaction between keratin fibers and ethylenically unsaturated compounds most readily takes place in the presence of water. This generally presents no problem since only small amounts are necessary for this improvement and since the catalyst components and/ or monomers are generally applied to the fibers in an aqueous medium. If the substrate is dry at the time of treatment, the reaction rate will be slower. Consequently, it is preferred that the substrate be wet with water when the reaction takes place. Ionic or non-ionic surface active agents may be utilized in any aqueous medium used in applying the reagents.

In the presence of the above systems, it is believed that the ethylenically unsaturated compounds react with the keratin fibers, although the mechanism of the reaction is by no means completely understood. It is known, however, that when butyl acrylate or another ethylenically unsaturated compound of the desired class is applied to keratin fibers in the presence of one of the above initiating systems, the resulting keratin fibers increase considerably in weight, and the reacted compounds cannot be readily remove-d by extraction techniques utilizing solvents for the homopolymers of such compounds. It is, consequently, believed that the reacted compounds to a large extent are covalently bonded to the keratin fiber molecule. Reacted compounds bound by other forces and which may be extractible provide improved results also, but often at the sacrifice of aesthetic properties.

The reaction of the above monomers or their derivatives with keratin fibers may be conducted at room temperature, although temperatures between about 40 and 60 C. are generally preferred. A temperature in excess of about 100 C. is generally not preferred, since undue degradation of some of the components of the preferred catalyst system, the redox system, occurs at this elevated temperature. In general, such conditions as concentrations of the reagents, pH, time and temperature of reaction may be modified to suit the individual circumstances, while still providing the desired degree of reaction.

The fibrous substrate may be exposed to the monomer in vapor, liquid or emulsion form. Exposure to the vapors of the monomers is conveniently carried out by entraining the vapor in an oxygen free gas, such as nitrogen, and then interposing the substrate in a stream of the gas and vapor. Inert volatile liquids, such as water or an alcohol, may be mixed with the compound being vaporized. Similarly, the fibrous substrate may be immersed in a liquid system, either solution or emulsion type, containing the desired amount of monomer.

Any desired apparatus may be used to apply one or more of the above class of ethylenically unsaturated COlTlpounds to keratin fibers, such as by padding, spraying or the like, but preferred apparatus includes forced-flow equipment, such as disclosed in the copending application Ser. No. 243,671, now Patent 3,291,560. With this apparatus, the desired systems can be repeatedly forced back and forth through keratin fibers at controllable flow rates to provide particularly good reaction results.

While the process of this invention is particularly adapted to fibrous substrates composed essentially of keratin fibers, particularly those composed entirely of wool fibers, it is also applicable to substrates wherein synthetic or natural fibers are blended with keratin fibers and to blends with other keratin fibers, such as mohair, alpaca, cashmere, vicuna, guanaco, camel's hair, silk, llama and the like. The preferred synthetic fibers include polyamides, such as poly(hexamethylene adipamide); polyesters, such as poly(ethylene terephthalate); and acrylic fibers, such as acrylonitrile homopolymer or copolymers of acrylonitrile containing at least about 85% combined acrylonitrile, such as acrylonitrile/ methyl acrylate (85/ 15) and cellulosics, such as cellulose acetate and viscose rayon. Of the natural fibers which may be blended with the keratin fibers, cotton is preferred. In any such blend, the keratin fibers treated in accordance with this invention are preferably present in at least a major proportion.

In order to provide acceptable fabric aesthetic and physical properties, it is preferred to conduct the desired reaction on keratin fibers in relatively loose form, i.e., prior to processing into yarn as in top, tow, roving, sliver and the like. Fabrics produced from these fibers through conventional processing techniques are characterized by softer handle, better draperability and tear strength, among other improvements, even though more ethylenically unsaturated compound is present in the fabric than is possible when a fabric per se is treated. Similar improvement in fiat stability is obtained when yarns are treated and processed into fabric, but other aesthetic properties, such as handle, will be diminished by this less preferred technique.

In the following examples, the best modes, as presently known, of practicing the invention are shown.

Example I Onto the beam of a lO0-lb. capacity Gaston County package dye machine are wound 63 lbs. of wool top. The beam is then mounted over the perforated spindle, the machine is closed, and the wool is scoured for 30 minutes at 140 F. with 80 gallons of water containing 149 gms. of Synfac-905, a non-ionic wetting agent containing a nonylphenol-ethylene oxide (1/9 to l/2 molar ratio) condensation product and 429 gms. of acetic acid. During the scouring operation, as in all succeeding operations in this example, the liquids are forced back and forth through the wool at a cycle for 4 minutes outside to inside, 6 minutes inside to outside. After scouring, a redox catalyst system maintained at 100 F. and composed of 63 gms. of Fe(NO 429 gms. of 50% H and 75 gallons of water, adjusted to a pH of 1.35 with 12 lbs. of H 80 is passed through the wool for '20 minutes. The flow rate of the system through the wool is measured at about 120 gallons per minute.

Nineteen lbs. of butyl acrylate are then added to the recirculating catalyst solution and the resulting system is run for 20 minutes at 120 F. The remaining monomer, 57 lbs. butyl acrylate, is added to the system continuously until expended, about 1% hours. The reaction is continued for an additional 3 hours, after which the machine is drained and the wool is washed with water at 75 F. for 20 minutes. As a finishing operation, the wool is then impregnated with 80 gallons of Water containing 4% Arquad 16-50, a hexadecyl trimethylammonium chloride lubricant, and 1% Synfac-905 for 30 minutes at 120 F.

The wool top treated in this manner is found to have increased in weight by 75%. After boiling in acetone for one hour the wool top is found to weight approximately the same.

A 4-inch length of the top treated in this manner weighing about 19 milligrams is mounted as a tight loop with a -mil. diameter piano wire. The loop is then pressed at about 100 lbs. per square inch at 300 F. for 3 minutes in a hydraulic press. The pressed loop is then placed in water, heated to 120 F. for 20 minutes, dried, and the angle formed by the creased top is measured at 141, as compared to an angle of 162 for a similar length of untreated wool top.

The fibers so treated are processed into yarn which is then knitted into a jersey-type fabric. This fabric lies flat without curling at the edges while laying on a flat table. The fabric is then cut lengthwise with a pair of straightedge scissors to the entire length of the fabric. The cut edge remains flat on the table. When this latter procedure is conducted on a similar knitted fabric but composed of untreated wool fiber, the cut edge curls to a great extent towards the center of the fabric. A woven fabric similarly remains flat after cutting. This fabric is also immersed in water at 140 F. for one hour and is found to shrink in area by grater than 25%, indicating it could be felted if desired.

Example II Similar results are obtained when a fabric is produced from fibers having reacted therewith ethyl acrylate to 90% pickup (154 retained crease angle), ethyl acrylate to a pickup of 117% (retained crease angle of 147), methylmethacrylate and butyl acrylate in equimolar ratios to a pickup of 68% (retained crease angle of 112),

styrene and butyl acrylate in a molar ratio of l to 3 to pickup (retained crease angle of 148), acrylonitrile and butyl acrylate in a molar ratio of 1 to 3 to a pickup of 101% (retained crease angle of acrylonitrile and ethyl acrylate in a molar ratio of l to 3 to a pickup of 111% (retained crease angle of 113), and methylmethacrylate and ethyl acrylate in a molar ratio (1); 4 )to 1 to a pickup of 94% (retained crease angle of That which we claim is:

1. A process of producing fabrics having improved properties comprising reacting with keratin fibers at least one ethylenically unsaturated compound having, in polymer form, a glass transition temperature less than about 40 C. and with at least one ethylenically unsaturated compound having, in polymer form, a glass transition temperature greater than about 50 C., the compound having the lower glass transition temperature being present in at least a major proportion, the total weight increase in said fibers being greater than about 50%; and knitting a fabric containing said fibers in at least a major proportion, said fabric being characterized by a high degree of fiat stability and feltability.

2. The process of claim 1 wherein the ethylenically unsaturated compound comprises an acrylic acid ester of a saturated aliphatic monohydric alcohol.

3. The process of claim 2 wherein the ethylenically unsaturated compound comprises butyl acrylate.

4. The process of claim 2 wherein the ethylenically unsaturated compound comprises 2-ethyl hexyl acrylate.

5. A fabric prepared in accordance with the process of claim 1.

References Cited UNITED STATES PATENTS 2,406,412 8/1949 Speakman et a1. 1l714l 2,940,869 6/1960 Graham 8 2,956,899 10/1960 Cline 8 3,005,730 10/1961 Pal'do 117-l41 3,008,920 11/1961 Urchick 8 3,083,118 3/1963 Bridgeford 8--128 3,031,334 4/ 1962 Lundgren 8-127 OTHER REFERENCES -Lipson et al.: Formation of Polymers in Textile Fibres, Nature, vol. 157, No. 3992, May 4, 1946, p. 590.

J. TRAVIS BROWN, Primary Examiner.

I. CANNON, Assistant Examiner.

U.S. C1. X.R. 

1. A PROCESS OF PRODUCING FABRICS HAIVNG IMPROVED PROPERTIES COMPRISING REACTING WITH KERATIN FIBERS AT LEAST ONE ETHYLENICALLY UNSATURATED COMPOUND HAVING, IN POLYMER FORM, A GLASS TRANSITION TEMPERATURE LESS THAN ABOUT 40*C. AND WITH AT LEAST ONE ETHYLENICALLY UNSATURATED COMPOUND HAVING, IN POLYMER FORM, A GLASS TRANSITION TEMPERATURE GREATER THAN ABOUT 50*C., THE COMPOUND HAVING THE LOWER GLASS TRANSITION TEMPERATURE BEING PRESENT IN AT LEAST A MAJOR PROPORTION, THE TOTAL WEIGHT INCREASE IN SAID FIBERS BEING GREATER THAN ABOUT 50%; AND KNITTING A FABRIC CONTAINING SAID FIBERS IN AT LEAST A MAJOR PROPORTION, SAID FABRIC BEING CHARACTERIZED BY A HIGH DEGREE OF FLAT STABILITY AND FELTABILITY. 